The effect of water on granular liquid flows: from debris to mud flows

TL;DR

This paper investigates how water influences granular liquid flows, linking rheology to velocity fluctuations, and introduces effective Navier-Stokes equations for different regimes, highlighting turbulence characteristics distinct from Newtonian fluids.

Contribution

It develops a rheological framework connecting granular suspension behavior to velocity fluctuations and compares it with geophysical models, revealing unique turbulence scaling laws.

Findings

Presence of a direct kinetic energy cascade in turbulent flows

Distinct turbulence scaling laws from Newtonian fluids

Effective Navier-Stokes equations applicable to different flow regimes

Abstract

In this work, we show how the rheology of granular suspensions can be related to the properties of the fluctuations of the velocity field inside the medium. In particular, effective Navier-Stokes equations in the different flow regimes are constructed and compared to an actual geophysical model that was so far purely phenomenological. Then, it is shown that a direct cascade of kinetic energy is present when the flow becomes turbulent, but with a scaling law that is quantitatively very different from that of usual Newtonian fluids.